Lustered wool product and method of making the same



tates V 3,051,544 LUSTERED WOOL TPRGDUCT AND IVETHGD OF MAKING Til-E SAD E Harold W. Wolf, Clifton, and Werner von Bergen, North Caldwell, N.J., assignors to J. P. Stevens & (30., Inc.,

New York, N.Y., a corporation of Delaware No Drawing. Filed Feb. 12, 1959, Ser. No. 792,726

8 Claims. (Cl. 8-128) This invention relates to a raised woolen fabric having exceptionally stable high luster and also, it relates to the method by which such a fabric is made.

Conventionally, a luster finish on fabrics such as velours, fleeces, suedes, duvetynes, zibelines, broadcloth and plushes is produced by a series of finishing operations involving hot water or steam treatments such as crabbi-ng, blowing or decatizing and potting or roll boiling in combination with mechanical operations of raising (gigging and napping), brushing, shearing, beating and plushing. The desired resulting luster may vary from a soft subdued luster to a high glossy luster depending on the orientation and straightening or deciimping of the individual fibers as well as the smoothness of the fabric surface.

One serious disadvantage of the luster produced the conventional way, especially when it comes to the high luster finish, is its poor stability against moist steam and high humid conditions. This is especially detrimental in the tailoring of high luster fleeces and plushes for ladies coats. In this type of tailoring it is necessary to treat certain parts of the coats with moist steam of the Hoffrnan Press. Generally a fifteen second steaming is sufficient to vitiate the luster by disarranging and crimping of the wool fibers, thereby destroying the smoothness of the fabric surface.

This invention relates to a combination of chemical and mechanical treatments to modify the keratinous material such as wool, hair and the like, that after the orientation and straightening of the individual fibers they will no longer contract, returning to their original, normal crimpy state as Well as their position relative to the woven base of the fabric. The essential wet chemical treatments considered in the present invention to produce the stable lustrons fabrics are operations following or running concurrent-1y with the napping or plushing, where the chemical treatments enhance the luster and promote a high stability of the fiber alignment and orientation by the addition of suitable chemicals. These chemical treatments also serve to reduce the number of normal operations outlined above to give a required degree of luster.

Wool, one of the most important members of structural proteins-keratin has been shown to exist in two different molecular configurations, the (at-keratin and (id teratin. In wool keratin, the polypeptide chain is folded and, in addition to the zigzag form, assumes a helical form as in the case of tat-keratin. The adjacent chains are held by interconnecting cystine linkages or disulfide bridges as well as H bonds. The elasticity of wool fiber as well as its relative inertness and insolubility is related to these numerous cystine SS bridges between the chains and probably to a lesser degree to the H bonds. In particular, the SS bridges or bonds are afiected in the chemical treatements to be discussed to achieve reformed crosslinks or replace the broken linkages with more stable ones to give permanent set to the wool fiber. These SS bonds may be broken by various chemical agents, and may be subsequently reformed as new crosslinkages by the method of the present invention. It is in this way that the natural resistance of wool to contract and return to its original normal crimpy state can be overcome to a degree not obtainable to exposure to normal processes involving heat and moisture alone.

7 appreciate the technique to use.

Support for the above theory is found in the noted drawbacks of more recent discoveries in orienting raised fibers protruding from hides of sheep skins and the body of woven fabrics. For example, recent investigators have sought to improve the quality of raised woolen fabrics by processing the wool and then setting it with a conventional cross-linking agent such as formaldehyde. Here again, we find that the woolen fabric does not have stability or permanency of luster. From the various methods employed in the manufacture of commercially available raised Woolen fabrics, it was apparent that the problem would be difiicult to solve. As a matter of fact, the length of time that the problem has existed bears testimony to the fact that the solution was not readily foreseeable.

Therefore, an object of this invention is to provide a unique raised woolen fabric having exceptional luster and permanency of luster under service conditions as described earlier.

Another object is to provide a method by which exceptionally stable high luster raised woolen fabric can be produced.

Other objects and advantages will become apparent from the following description and explanation thereof.

in accordance with our understanding of the theory of the present invention, in order to procure a stable high luster raised woolen fabric, the following combination of steps is employed, and while the manner in which the individual step is eifeoted may influence the degree of luster and permanency thereof it does not alter the advantages accruing over products prepared by conventional techniques. Our process comprises treating the raised fibers of a napped woolen fabric to effect substantial cleavage of cystine linkages thereby rendering the fibers more pliable or orientable, set-ting the treated fibers, and straightening the orientable fibers to achieve a high order of luster.

Napping a woolen fabric is a conventional practice which involves raising from the body of the fabric, a layer of fibers which protrude from the surface. The manner in which napping is conducted depends upon the final fabric sought, namely, suede, duvetyn, velour, fleeces, etc; however, any skilled person in the art would readily Generally speaking,'the process for raising is accomplished by gigging (teaselin-g) and by napping, by means of rotating rollers, drums or the like which are covered with teeth-like projections in the form of teasels or wire card clothing for pulling and/ or lifting fibers from the fabric to a raised position. After normal raising, the protruding fibers are characteristically curly and randomly oriented.

One of the features of the present invention is that chemical treatment renders the raised fibers pliable or orientable to the extent that it would be possible to achieve uniform orientation of straightened fibers. Rendering the fibers into a pliable condition may be accomplished immediatcly after napping, during napping or shortly before the straightening operation or during the straightening operation. In any event, the raised fibers must be rendered orientable before straightening or even during the same so that maximum luster is obtained.

Rupturing cystine linkages is another step which will be apparent to those skilled in the art. Having once discovered that the cystine linkages must be cleaved or ruptured, the technique became readily apparent. The treatment involves the use of a conventional reducing agent for cystine linkages of Wool containing material. The reducing agents are a well-recognized class. Since we are dealing with a woolen fabric, the reducing agent employed is one which does not cause harm or in any way afiect the ability of the fabric to be dyed or further processed as may be required. Generally, for the reduction reaction the following groups or classes of com- (1) Reaction with thioglycolic acid:

(2) Reaction with bisulfite:

(3) Reaction with hydrosulfite:

RSfiSR+Na2S204'- RSS204N3.

For the reducing treatment, an aqueous solution and/ or dispersion containing about 0.1 to 10% by Weight of reducing agent may be used. The concentration may be varied outside the range, but less satisfactory results are procured. In the case of the relatively more reactive reducing agents, such as the thio compounds, e.g., thioglycerol, thio-acid or salts thereof, which react at ambient temperature, it is preferred to use 0.1 to 4% by weight of the agent in an aqueous medium. The relatively less reactive agents viz. other than the thio compounds, are employed preferably in concentrationsof about 1 to 5% at elevated temperatures. The quantity of the reducing agent to be used may be determined on a wool basis which, for our invention, may be about 0.05 to 1% 'by weight. In the case of the thio compounds, it is preferred to use about 0.1 to 0.7%, based on the weight of wool being treated.

The temperature of reduction could vary from ambient level up to about 500 F. The temperature of reaction will depend on the type of reducing agent and the concentration thereof. With this in mind the period of treatment varies in accordance with the temperature of treatment. When ambient temperature is employed, the time usually varies fiom about 3 minutes to hours, Whereas at an elevated temperature such as 100 to 500 F., the time may vary from about 0.1 second to 2 minutes. The period of treatment varies inversely as the temperature of treatment. Here again, the above described conditions may be varied outside the enumerated range without departing from the invention.

Normally, the pH of wool may vary from 1.8 to 11. It is desirable to conduct the reduction treatment at a pH ofabout 4 to 8. Since the reducing agents may give wide differences in pH, an alkaline or acidic reagent may be employed to adjust the pH to within the range of 4 to 8. Here again, the type of alkaline or acidic reagent for pH adjustment of wool is readily understood by those skilled in the art. The kind of reagents for this purpose can be, for example, ammonium hydroxide, acetic acid, formic acid, etc.

The reducing treatment whereby the cystine linkages of the W001 material are ruptured may be accomplished concomitantly. with the reforming or setting step in which a crosslinking agent of the type to be discussed hereinafter is employed. The reducing agent is in solution or dispersion with the cross-linking agent, and in practice the solution is applied to the napped or raised fabric. Such a procedure is very efiective and economical, resulting in a product which is better in luster and stability towards steam than the product of any other method. Another alternative procedure is to apply the reducing agent toxthe. raised. fabric first, followed immediately "by the 4 treatment with the cross-linking agent. The fabric so treated may be straightened as discussed hereinabove.

When the operation involves reducing and reforming in sequence, following the application of reducing agent, 5 the fabric may contain from about 10 to 80% by weight of reducing solution, based on Wool. The impregnated fabric may 'be processed through the straightening step. The straightening operation is effected by conventional equipment, which may consist of a drum heated to a 10 temperature of about 300 to 500 F. and containing a serrated or comb-like member projecting from the surface along the length of the drum. As the raised fibers are combed or straightened in their pliable condition, uniform orientation is also achieved to an extent never before realized. At the elevated temperature, the reduction or cure is enhanced or completed during the straightening operation. The presence of moisture tends to further improve the pliability of the fibers. The number of times that the fabric is subjected to a brushing and straightening action depends not only on the pressure and temperature of the rotating cylinder, 'but naturally on the desired .final luster.

In the sequential treatment mentioned above, once the fibers have been straightened and uniformly oriented, the luster is exceptionally good. To stabilize the luster, it is set with what is usually termed as a cross-linking agent in wool chemistry. These cross-linking agents are well known to those skilled in the art and include such compounds as the aliphatic aldehydes, e.-g. formaldehyde or glyoxal; alkyl dihalides, e.g. ethylene dibromide, trimethylene dibromide or di-iodomethane; chloromethyl ethers; etc. The agents are emulsified in water to form aqueous mediums containing about 5 to 10% by weight of agent. Usually the emulsion is buffered with the usual agents such as sodium dihydrogenphosphate to provide a pH of about 8, or in the range of about 7 to 9. The aqueous material can be added to the raised fibers by spraying, brushing or a dipping operation. Usually about 0.0005 to 0.010 mol of cross-linking agent are added per gram of woolen fabric. For the alkyl dihalides it is preferred to use about 0.0005 mol per gram of wool, whereas for the aldehydes it is a low as 0.005 mol per gram of wool. Since any wet treatment such as the application of the cross-linking agent tends to disturb the alignment of the fibers and reduces the luster it may be be desirable to subject the wool to another straightening treatment. A

As a result of our invention, raised wool not only has increased luster but it is also exceptionally stable in this regard. In order to afford a basis for distinguishing the stability of our product from that of conventional materials, the following test was devised:

The luster was measured at the outset in terms of visual change. The sample of raised fabric was then subjected to live steam for 15-30 seconds at a temperature of about 240 F. on a Hoffman Press operating with a gauge pressure of p.s.i. At the end of this period, the steam treated cloth was again measured for luster. In the case of products of our invention, the 60 luster was stable to at least 15 seconds steaming whereas for conventional products the luster dropped to Zero.

To provide a better understanding of our invention, reference will be had to the following specific examples.

Example 1 A piece of velour fabric containing alpaca and wool dyed with milling colors at a cloth pH of 5.8 and weighing 10.8 kilos, was treated in accordance with the method of this invention. The first step in the process was to 0 apply by means of a continuous brush applicator a 1.5% alpha monothioglycerol solution at a buffered pH of 7 to give a Wet pick-up of 40%, providing approximately 0.6% monothioglycerol on the weight of wool. The wet fabric was immediately passed through a mechanical lustering operation employing a machine of the type described in Modern Textiles, March 1957, page 50, at a speed of 4 /2 yds./rnin. with a cylinder roll temperature at 430 F. After the mechanical treatment, the fabric was given a second wet application with a solution of formaldehyde at a concentration of 3% and pH of 3.8. The wet pick-up was 31%, resulting in a calculated formaldehyde content of 0.9% on the weight of wool. The fabric was then given two successive treatments through the mechanical lustering machine at the above settings. The fabric finally was dried. The fabric product exhibited excellent resistance to open steaming for 30 seconds on a conventional Hofiman Press using 60 p.s.i steam supply. In the case of the control sample, the luster was almost completely obliterated after 15 seconds of steaming. The hand and initial luster were also considered superior to the normally treated fabric. The alkali solubility of the treated fabric was under Thickness measurements made on the control and treated samples by means of a compressometer showed that 30 seconds steaming increased the thickness of the untreated fabric over 0.020 inch, while the treated fabric increased not over 0.015 inch.

Example 2 A 100% wool velour was treated in similar manner to Example 1 except that slightly higher amounts of treating agents were applied with the continuous brush applicator. In the first step, 1.6% alpha monothioglycerol solution was applied to the raised fabric to provide a wet pick-up of 58% and then mechanically lustered as described in Example 1. The second chemical treatment was made with a 3.2% formaldehyde solution to give approximately the same wet pick-up as in Example 1, namely, about 34%. The fabric was then mechanically lustered twice after the formaldehyde treatment and dried. The product had good luster retention for at least secends when subjected to open steaming on the Hoffman Press. The control sample or untreated fabric lost its entire luster in 15 seconds of steaming. The thickness of the steamed treated product was over 0.005 inch tbinner than the comparative control sample after 15 seconds open steaming thereby indicating a significant retention of fiber orientation.

Example 3 The general procedure of Example 1 was followed except in treating a sample of 100% wool velour. The treating solutions consisted of the mechanical lustering with a two component solution containing 1.4% alpha monothioglycerol and 3% formaldehyde, respectively. By means of the brush wet applicator, 68% of the solution was applied to the fabric. The mechanical lustering treatment was carried out in four stages, with the cylinder at varying temperatures, namely, but being lower during the initial stages, first pass at 350, second pass at 380 and third and fourth passes at 400 F. The product was stable to steaming for at least 15 seconds on the Hoffman Press.

Example 4 The procedure of Example 1 was employed except that the chemicals were applied by air spray to the fabric instead of brush application. The results were the same in so far as steam stability was concerned, but better control of the amounts of applied chemicals was realized by the spray technique.

Example 5 A velour fabric was sprayed with an emulsion consisting of 10% trimethylene dibromide and 1.5% sodium sulfoxylate, and having a pH of 7.4. The spray was adjusted to produce a wet pick-up of approximately 25%. The treated fabric, after the reaction was allowed to stand for 35 minutes before being passed twice through the mechanical lustering machine. The cylinder of the lustering machine was adjusted to 430 F. and the machine was operated at a cloth speed of 4 /2 yds./min., using a pressure set of 9. Improved luster retention or stability to steaming was noted over Example 1.

Example 6 Using the spray method of Example 5, a wool fabric was treated with a solution containing 1% formaldehyde and 2% sodium sulfoxylate at a pH of 5 and 25 C. The fabric was lustered as in Example 5.

Example 7 A wool velour fabric was impregnated with a solution of formalin, one part of formalin was diluted with 14 parts of water, by means of a turbo wet applicator, resulting in approximately 57% wet pick-up. After standing /2 hour, the wet fabric was processed three times through the lustering machine, operated with the cylinder temperature at 430 F. and a cloth speed of 4 /2 yds./min. The luster retention was considered good after being subjected to 15 seconds of open steaming on the Hoffman Press.

Example 8 in this test, a velour fabric was treated by a pad application of the chemical prior to the mechanical lustering. The velour fabric was treated with a solution containing 1% monothioglycerol at a pH of 7. Using a conventional pad consisting of immersion tank and squeeze roll assembly (cylinder pressure of p.s.i.), the fabric had a wet pick-up of 35%. The wet pick-up was then reduced to 1520% by drying. Following this operation, the fabric was padded with 3% formaldehyde solution and the moisture content reduced to 15-20%. The fabric was then processed twice through a mechanical lustering machine at 5 yds./min. and with cylinder temperature at 430 F. Good luster retention was observed in the fabric so treated.

Example 9 A raised fabric containing 70% wool and 30% mohair was dipped or padded into a solution containing 1% by weight of monothioglycerol and 3 /2 by weight formaldehyde, adjusted to a pH of 5-6 by means of ammonia, at 65 F. to provide a wet pick-up of 55%. The fabric was rolled and allowed to stand for 1 hour. The moisture content of the fabric was reduced to 30% by drying at F. The partially dried fabric Was lustered or straightened on the lustering machine operated with a cylinder temperature of 400 F. and a cloth speed of 5 yds./min. The product had excellent stability to steam, measured by the Hoffman Press, as compared to the stability of other steamed treated fabrics and control samples.

We claim:

1. A process which comprises treating a raised woolen fabric containing raised fibers with a wool reducing agent to cleave cystine linkages thereof thus rendering the raised fibers orientable, treating the orientable fibers with a re-cross-linking agent and subjecting the fibers so treated to a straightening operation to produce a high luster whereby the same are oriented uniformly and set.

2. The process of claim 1 wherein the reducing agent is selected from the group consisting of alkali metal bisulfites, ammonium bisulfite, zinc-, ammonium-, alkali metal-hydrosulfites, a thioglycerol containing one to three sulfhydryl groups, and HSRCOOM where R is an alkyl group containing one to six canbon atoms and M is selected from hydrogen, zinc, ammonium, and alkali metals.

3. The process of claim 1 wherein about 0.1 to 10% of reducing agent is employed to obtain 0.05 to 1% of reducing agent on the wool and the re-cross-linking agent is employed in a concentration of about 5 to 10% to provide about 0.0005 to 0.01 mol of re-cross-linking agent per gram of wool.

4. The process of claim 1 wherein the straightening operation is conducted at a temperature of about 300 to 500 F. g

5. A process which comprises first treating a raised woolen fabric containing raised fibers with a wool reducing agent to cleave cystine linkages thus rendering the raised fibers orientable, subjecting the orientable fibers to a straightening operation whereby the same are oriented uniformly to produce a high luster, and then treating the oriented fibers With a wool re-cross-linking agent to set the oriented fibers.

6. A process which comprises treating a raised woolen fabric containing raised fibers with a mixture of a wool reducing agent and a wool re-cross-linking agent, and subjecting the resultant wool-fabric to a straightening operation to impart a high luster, whereby the fibers are oriented uniformly and set.

7; A process whichcomprises treating a raised Woolen fabric containing raised fibers with about 0.1 to 4% of an aqueous solution of a thioglycerolto provide about 2 0.1 to 0.7% of monothioglycerol based on the wool thus rendering the fibers orientable, treating the orient- References Cited in the file of this patent UNITED STATES PATENTS 1,949,384 Weyner Feb. 27, 1934 2,434,562 1948 0,739,033 1956 2,836,543 1958 2,955,0l6 1960 OTHER REFERENCES-- 

1. A PROCESS WHICH COMPRISES TREATING A RAISED WOOLEN FABROIC CONTAINING RAISED FIBERS WITH A WORL REDUCTING AGENT TO CLEAVE CYSTINE LINKAGES THEREOF THUS RENDERING THE RAISED FIBERS ORIENTABLE, TREATING THE ORIENTABLE FIBERS WITH A RE-CROSS-LINKING AGENT AND SUBJECTING THE FIBERS SO TREATED TO A STRAIGHTENING OPERATION TO PRODUCE A HIGH LUSTER WHEREBY THE SAME ARE ORIENTED UNIFORMLY AN SET. 